Web feeding and changing assemblies are well known in the art, as typically illustrated by U.S. Pat. Nos. 3,944,151 (issued to LEE et al on Mar. 16, 1976); 5,354,006 (issued to RODER on Oct. 11, 1994); 5,253,819 (issued to BUTLER, Jr., on Oct. 19, 1993); and 5,356,496 (issued to LINCOLN et al on Oct. 18, 1994).
These conventional web-transition assemblies typically exchange a new web of material for a used web, while the old web material is still being conveyed. In this way, the webs are changed "on the fly". A common mechanism for accomplishing this web transition is known in the art as a "bump splicer". The new, unused web comprises an adhesive surface that attaches to the old web through their "bumping" together, as they are simultaneously being conveyed. Thereafter, the web material trailing from the preceding, "old" web is severed at the splice; thus is the transition in the continuous, web-conveying process accomplished.
Exchanging an old web for a new web is a fairly common procedure. However, this procedure represents a long-standing problem, particularly when the web materials comprise backing. Backing material from each web poses a particularly vexatious problem in accomplishing the transition from one web roll to another, since two layers on each web roll must be handled. Not only must each backing be unwound and stored as each web is advanced, but they must also somehow be positioned out of the splicing, or bump zone, so that they do not interfere with the splice mechanism. Despite the profusion of mechanisms and assemblies for changing web materials on the fly, the splicing of a web with a backing was only recently accomplished, as illustrated in U.S. Pat. No. 5,692,698, assigned to a common assignee.
This invention accomplishes the bump splicing of a web with a backing in a more facile, and advantageous manner than its predecessor system. The bump splice mechanism of this invention is less complicated than the revolving turrets of the aforementioned patent. The mechanism of the invention comprises simplified work stations that have movable threading assemblies. The threading of the web can be accomplished at a distance from the exhausting web, thus providing a threading system that is more reliable, convenient, and safer.
Another advantage of the current inventive system resides in its ability to provide for threading the backing material either clockwise or counterclockwise from the web supply roll.
Still a further advantage of the current invention is that the fresh web can be attached to the exhausting web in two different modes: either when the exhausting web is at rest, or when the exhausting web is moving.